I was debating posting this here or in the Science and Measurement board because this is for a research projects, but I am trying to source a flow sensor, so I figured that this would be the best spot. I have looked through the forums,
I am trying to find a water flow sensor that can register at least between 10 ml/min and 200 ml/min, but it is proving to be very difficult to find one. Most sensors that I can find for Arduinos start around 300 ml/min and go up from there, and the closest that I have found is 40–150 ml/min. I am trying to stick with either 12V or 5V for components, but I can probably make a line on the breadboard for 3.3V if need be. Most of my fittings for the system that I am making are either 3/8 or 5/16, but I suspect finding a flow meter that can read this low of flow while having this large of inlet is going to be near impossible. I am going to be using different solutions, such as saline, low concentration detergents in water, or distilled water.
I'm still pretty new to Arduino as well, so I am trying to find something easy to work with.
One reason those are hard to find on the hobby market is that it is difficult to make flowmeters that are accurate at such low flow rates. The ones you can find at laboratory suppliers are therefore expensive.
What sort of accuracy do you require? For such low flow rates as 10 ml/min, does it even make sense to have a flowmeter, when you can very accurately dispense liquid at those rates, using peristaltic or syringe pumps?
Yeah, that's the challenge, ha ha. Based on experiments by others, they increased the flow rate over time by 1.5 ml every 30 min from 10 ml/min to 50 ml/min, another paper that I found used an average flow rate of 164 ml/min, and a lot of papers just used 200 ml. Because I am looking to publish the results, I am going to try to remain as accurate as possible. I am also hoping to use it as part of a sensor feedback loop to keep the pump flowing at a suitable rate. At this point though, I pretty much have to accept whatever accuracy I can get, ha ha.
True, but I am planning to use a gear pump because I want to be able to generate pulsatile flows, and the only paper that I have found that does this without a very expensive implantable cardiac device is with a gear pump (and conveniently, they used a Arduino Uno to control it; doi 10.1016/j.medengphy.2017.10.006). A syringe pump won't really work because I have going to be dealing with upwards of 120 L of solution, and I don't know that a peristaltic pump will be able to generate the type of pulsatile flow that I am looking at.
(Sorry, I probably should have put a bunch of this stuff in my original question so that people don't get annoyed with suggesting solutions that I should have clarified earlier.)
Yes, and if you want actually useful answers, quantify terms like "pulsatile" flows.
None of this has anything to do with Arduino, although as you have learned, Arduino can be used to control and/or interface with very expensive pieces of equipment.
That's why I was specifically asking about sourcing a sensor that is compatible with Arduino and not going into the details of my experiment (which I can go on for pages about, but that isn't relevant to the requirements of the sensor). By pulsatile, I mean physiological pulse between 80 mmHg and 120 mmHg (1.5–2.3 psi), but I have already sourced a pump and pressure sensor for all of that that are Arduino compatible.
I just need to find a sensor that is capable of measuring flow between 10 ml/min and at least 200 ml/min, and I have the rest of the system figured out. I appreciate the suggestions, but you can hopefully see why I asked what I did in hopes of staying out of the weeds of my experiment details.
Arduino is probably the easy part, but you are out of the range of common-or-garden turbines by an order of magnitude, and probably need a dosing facility - with a wallet to match.
Similarly, your upper limit may be beyond the ability of a device that counts drops.
After another day of searching I might have found a sensor that will work, and it can read from 4 ml/min and up (with an accuracy of ±5% or 0.5 ml/min up to 300 ml/min) but it's also $200. The nice thing is that there is Arduino libraries for using it, so that should help.
It runs on 3.2 - 3.8 V and my , and it's a 1/4" (6 mm) barbed fitting, but I can probably find ways to make that work.
A pulse flow is going to cause further issues with accuracy as the flow rate is not constant with time and a meter will have a reaction time . I too would look at the pump end instead - piston pump both variable stroke ??
A piston pump is going to have a lot of inconsistent flow rates too though, even with a double acting pump. One thing that I found was that if you have the sensor far enough away, it tends to even out the flow and there is less variability due to the decrease of turbulence in the flow.
That's true, the volume is a linear function of pressure, and I will have a pressure sensor in the system. Though it is definitely not the ideal placement, I was looking at having the flow sensor before the pump (flow in is not going to be much different than flow out). Because of some of the changes in tubing diameter in the set-up (the joys of trying to source parts that weren't really intended to run together), there is going to be changes in pressure through the system until after the pump, and I don't really want the headache of having to do Bernoulli's principle calculations that frequently and hopefully not miss something.